Glioma is a common type of primary brain tumor, accounting for about 33% of these tumors. Gliomas originate in the glial cells in the brain. Glial cells are the tissue that surrounds and supports neurons in the brain.
These tumors arise from three different types of cells that are normally found in the brain: astrocytes, oligodendrocytes, and ependymal cells. Gliomas are called intrinsic brain tumors because they reside within the substance of the brain and often intermix with normal brain tissue.
There are different grades of gliomas; however, they are most often referred to as “low-grade” or “high-grade” gliomas. The low or high grade designation reflects the growth potential and aggressiveness of the tumor.
Glioblastoma multiforme (GBM) is the most common and most aggressive malignant primary brain tumor in humans, involving glial cells and accounting for 52% of all functional tissue brain tumor cases and 20% of all intracranial tumors. Despite being the most prevalent form of primary brain tumor, GBM incidence is only 2-3 cases per 100,000 people in Europe and North America. According to the WHO classification of the tumors of the central nervous system, the standard name for this brain tumor is “glioblastoma”; it presents two variants: giant cell glioblastoma and gliosarcoma.
Treatment can involve chemotherapy, radiation, radiosurgery, corticosteroids, antiangiogenic therapy, surgery and experimental approaches such as gene transfer.
With the exception of the brainstem gliomas, glioblastoma has the worst prognosis of any central nervous system (CNS) malignancy, despite multimodality treatment consisting of open craniotomy with surgical resection of as much of the tumor as possible, followed by concurrent or sequential chemoradiotherapy, antiangiogenic therapy with bevacizumab, gamma knife radiosurgery, and symptomatic management with corticosteroids. Prognosis is very poor, with a median survival time of approximately 12-14 months and is almost invariably fatal.
The current therapeutic modality for glioma includes surgery, radiotherapy, and chemotherapy. The most widely used drugs are carmustine, lomustine, vincristine, procarbazine, carboplatin, etoposide and irinotecan. Neoadjuvant or adjuvant therapy with these drugs was shown to prolong disease-free survival but not overall survival. Recently, concurrent temozolomide and radiotherapy has become the new standard of care for patients diagnosed with GBM, prolonging survival from 12 months to 15 months.
However, there still exists a pressing need for novel treatment modalities to treat and cure GBM and related cancers,